add type filter to scan function

Fixed #1220

3 files changed, 29 insertions, 5 deletions

diff --git a/CHANGES b/CHANGES
index 074fac6..c200eea 100644
--- a/CHANGES
+++ b/CHANGES
@@ -19,6 +19,7 @@
       specified in the SSL cert. By default 'ssl_check_hostname' is False
       for backwards compatibility. #1196
     * Slightly optimized command packing. Thanks @Deneby67. #1255
+    * Added support for the TYPE argument to SCAN. Thanks @netocp. #1220
 * 3.3.11
     * Further fix for the SSLError -> TimeoutError mapping to work
       on obscure releases of Python 2.7.
diff --git a/redis/client.py b/redis/client.py
index fba80c9..9d38c50 100755
--- a/redis/client.py
+++ b/redis/client.py
@@ -2058,34 +2058,49 @@ class Redis(object):
         return self.execute_command('SORT', *pieces, **options)
 
     # SCAN COMMANDS
-    def scan(self, cursor=0, match=None, count=None):
+    def scan(self, cursor=0, match=None, count=None, _type=None):
         """
         Incrementally return lists of key names. Also return a cursor
         indicating the scan position.
 
         ``match`` allows for filtering the keys by pattern
 
-        ``count`` allows for hint the minimum number of returns
+        ``count`` provides a hint to Redis about the number of keys to
+            return per batch.
+
+        ``_type`` filters the returned values by a particular Redis type.
+            Stock Redis instances allow for the following types:
+            HASH, LIST, SET, STREAM, STRING, ZSET
+            Additionally, Redis modules can expose other types as well.
         """
         pieces = [cursor]
         if match is not None:
             pieces.extend([b'MATCH', match])
         if count is not None:
             pieces.extend([b'COUNT', count])
+        if _type is not None:
+            pieces.extend([b'TYPE', _type])
         return self.execute_command('SCAN', *pieces)
 
-    def scan_iter(self, match=None, count=None):
+    def scan_iter(self, match=None, count=None, _type=None):
         """
         Make an iterator using the SCAN command so that the client doesn't
         need to remember the cursor position.
 
         ``match`` allows for filtering the keys by pattern
 
-        ``count`` allows for hint the minimum number of returns
+        ``count`` provides a hint to Redis about the number of keys to
+            return per batch.
+
+        ``_type`` filters the returned values by a particular Redis type.
+            Stock Redis instances allow for the following types:
+            HASH, LIST, SET, STREAM, STRING, ZSET
+            Additionally, Redis modules can expose other types as well.
         """
         cursor = '0'
         while cursor != 0:
-            cursor, data = self.scan(cursor=cursor, match=match, count=count)
+            cursor, data = self.scan(cursor=cursor, match=match,
+                                     count=count, _type=_type)
             for item in data:
                 yield item
 
diff --git a/tests/test_commands.py b/tests/test_commands.py
index 00752fa..b2bd2da 100644
--- a/tests/test_commands.py
+++ b/tests/test_commands.py
@@ -1065,6 +1065,14 @@ class TestRedisCommands(object):
         _, keys = r.scan(match='a')
         assert set(keys) == {b'a'}
 
+    @skip_if_server_version_lt('5.9.101')
+    def test_scan_type(self, r):
+        r.sadd('a-set', 1)
+        r.hset('a-hash', 'foo', 2)
+        r.lpush('a-list', 'aux', 3)
+        _, keys = r.scan(match='a*', _type='SET')
+        assert set(keys) == {b'a-set'}
+
     @skip_if_server_version_lt('2.8.0')
     def test_scan_iter(self, r):
         r.set('a', 1)